Hydraulic brake



No. 6l5,l4!. Patented Nov. 29, I898. l .L. CLARK. HYDRAULIC BRAKE.

(Application filed. Oct. 11, 1897.)

3 Sheets-Sheet I.

(No Model.)

us ca, Pno'rouwo" A Nu. 6|5,l4|. Patented Nov. 29, I898. F. L. CLARK.

HYDRAULIC BRAKE.

(Application filed Oct. 11, 1897.)

3 Sheets-Sheet 2.

(No Model.)

WITNESSES: mvs TO M g M Att'y.

No. 6l5,'l4l. Patented Nov.'29, I898. F. L. CLARK;

HYDRAULIC BRAKE.

(Application filed Oct. 11, 1897.)

{No Modei.) 3 Sheets-Sheet 3.

UNITED STATES PATENT OFFICE.

FRANCIS L. CLARK, OF STEWART STATION, PENNSYLVANIA, ASSIGNOR TO THECLARK BRAKE COMPANY, OF PITTSBURG, PENNSYLVANIA.

HYDRAULIC BRAKE.

SPECIFICATION forming part of Letters Patent No. 615,141, dated November29, 1898.

Application filed October 11, 1897. Serial No. 654,844. (No model.)

To all whom it may concern: first to Figs. 1 and 2, I provide twobrake-cyl- Be it known that I, FRANCIS L. CLARK, of inders 6 6, ofsmaller and larger dimensions, Stewart Station, in the county ofWestniorerespectively, which are connected one to the land and State ofPennsylvania, have inother in line axially. The cylinder 6 is, as in- 55vented a certain new and useful Improve- Patent No. 574,663 aforesaid,provided with ment in Hydraulic Brakes, of which improvea main piston 51and a supplemental piston ment the following is a specification. 56 forthe purpose of automatically and con- My present invention relates toand is an tinuously taking up wear and slackness or improvement inhydraulic-brake cylinders lost motion of the rubbing surfaces in the op-60 [o and their accessories of the general charaO- eration of theapparatus, and, as in said patter of those set forth in Letters Patentof out, the main piston 51, which is of comparathe United States Nos.574,663 and 574,665, tively short traverse, is fitted in acountergranted and issued to me under date of Janbore at the end of thecylinder to which liquary 5, 1897, which exemplify means for preuid isadmitted, and its outward traverse in 65 [5 liminarily taking up theslack of the conneceffecting an application of the brakes is limtionsand the clearances between the brakeited by a shoulder 53 at the innerend of the shoes and the wheels and subsequently apcounterbore. Thesupplemental piston 56, plying the brake-shoes to the wheels by theagainst which the piston-rod 16 bears, is, as action of separate andindependent brakein said patent, fitted with suitable packing 7ocylinder pistons. in the smaller bore of the cylinder 6 beyond Theobject of my invention is to afford im-. the shoulder, and, asoriginally fitted, it abuts proved facilities for the performance of theagainst the main piston 51 and is moved by functions above stated withreliability and liquid subject to the pressure of said piston certaintyunder all conditions, as well as to 51 throughout the traverse of saidpiston in 75 minimize the power and quantity of liquidreeffecting anapplication of the brakes. A quired in the operation of the brake systemhelical spring 22, which bears against the and to properly andaccurately adjust and head of the brake-cylinder through which themaintain the normal degree of clearance bepiston-rod passes, returnsboth the main and tween the brake-shoes and the wheels when supplementalpistons to their normal posi- 8o 0 the brakes are off. tions upon therelease of pressure from the The improvement claimed is hereinafter mainpiston. fully set forth. In the construction set forth in Patent No.

In the accompanying drawings, Figure l is 574,663 a valvular mechanismwas fitted in a View, partly in elevation and partly in secthe pistons51 and 56 and the piston 51 was 85 5 tion, showing a brake-cylinder andcontrolprovided with a passage controlled by the ling-valve mechanismembodying my invenvalve of said mechanism for the admission tion; Fig.2, a partial transverse section of liquid to the space between thepistons. through the brake-cylinder at the line mac of Under my presentinvention a material sim- Fig. 1; Fig. 3, a view similar to Fig. 1,illusplification is effected by wholly dispensing 9o trating amodification in structural detail; with an internal mechanism andsubstitut- Fig. 4, a partial transverse section through ing an externalvalve 65, which performs the the brake-cylinder at'the line y y of Fig.3; functions of both the internal check-valve Figs. 5, 6, 7, and 8,partial longitudinal secand the independent hand-operated by-pass tions,on an enlarged scale, through the convalve of Patent No. 574,663. Thevalve 65, 5 5 trolling-valve and casing shownin Fig.3,illuswhichcontrols a passage 64, leading from the trating different positions ofthe valve; and larger bore of the cylinder 6, between the pis- Fig. SJ,a partial transverse section through tons 51 and 56, to the outer orsupply side of the brake-cylinder at the line y y of Fig. 3, the piston51, is fitted in a casing on the outillustrating a modification in themeans for side of the cylinder 6 and is normally held to 100 unseatingthe releasing-valve. its seat by a spring 67. The stem 66 of the In thepractice of my invention, referring valve is provided with a transversepin to the valve-casing.

69, which is fitted to traverse, with the stem, in a recess in aremovable cap 68, connected By unscrewing the cap slightly the bottom ofthe recess therein will abut against the pin 69 and unseat the valve.

A cylinder 6, of smaller bore than the cylinder 6, is connected to theouter end of the brake-cylinder 6 and closes said cylinder in the mannerof a head, the cylinders 6 and 6 being fully open one to the other. Apiston 51, which is formed integral with or otherwise fixed to the mainpiston 51 and is suitably packed, is fitted to traverse in the cylinder6.

The supply and discharge of liquid to and from the cylinders 6 and 6 forthe application and release, respectively, of the brakes is eifected byavalvular mechanism inclosed in a casing 10, the construction of whichmechanism will now be described. The casing 10 communicates bya lateralbranch pipe 5 with a delivery or pressure pipe which leads from aforce-pump or other source of pressure, and the opening of the branchpipe in the casing communicates by a pipe 5 with the cylinder 6 on theouter side of the piston 51. The outer end of the cylinder 6, andconsequently the space between the pistons 51 and 51, is connected withthe casing by a pipe 5", and the casing 10 is connected by a pipe 5controlled by an inwardly-opening check-valve 15, with a suction-pipe 5.The connection of the casing 40 and pipe 5 may either be a direct oneor, as shown, through the intermediation of a liquid-storage reservoir9. The pipe 5* is always open to the branch pressure-pipe 5 butcommunication between the pipes 5 and 5 is controlled by a check-valve42, which is normally seated and opens toward the pipe 5, and also by avalve 41, which is connected to a piston -13, of larger diameter, and isheld normally seated by a spring 44, bearing on said piston. Thecheck-valve 12 also controls communication between the branchpressure-pipe 5 and the port in the casing, which is governed by thecheck-valve and which communicates with the branch suction-pipe 5. Thethree valves 41, 42, and 15 lift in the same directionthat is to say,toward the branch pressure-pipe 5.

The relation and manner of operation of the brake cylinder 6, pistons 51and 56, and check-valve correspond in allessential particulars withthose of the similarly-numbered cylinder and pistons and the check-valve61 of Patent No. 571,663 and need not, therefore, be herein fully and atlength described, it being only necessary to note that, as in saidpatent, liquid is admitted by the checkvalve 65 to the space between thepistons 51 and 56 and moves the piston 56 outwardly sufficiently far totake up the wear of the brake-shoes 011 the wheels, so as to maintain auniform degree of clearance between the brake-shoes and the wheels. Whenthe piston 56 has by increase of wear and slackness been advanced so farin the cylinder as to prevent it from making as long a stroke as that ofthe piston 51, the cap 68 of the casing of the valve 65 is partiallyunscrewed, and said valve is thereby unseated, and the liquid isreleased from the space between the pistons 51 and 56 until they areagain brought in contact. Proper renewal or adjustment of the frictionalsurfaces and connections having been made, the further operation of thepistons is effected in preliminarily taking up slack, and thereforemoving together for application, as in Patent No. 574,663. It will beobserved that the valve 65 is not only more inexpensively applied andmore conveniently located for insertion, removal, and replacement thanthe valve 61 of said patent, but also by its capacity of being manuallyunseated that it performs both the functions of said valve and of theindependent by-pass valve 65 therein provided.

The operation of the valvular mechanism, which is inclosed in the casing40, in the application and release of the brakes is as follows, it beingunderstood that the space in the cylinders to the left of the piston 56is full of liquid and that excess slack has been taken up, forcing thepistons 51 and 56 apart, so that they do not touch each other, but areheld apart by the liquid between them: Liquid from the branchpressure-pipe 5 passes through the pipe 5 into the smaller cylinder 6 onthe outer side of the piston 51 and forces said piston, together withthe pistons 51 and 56, to the right, this preliminary movement of thepiston serving to fully take up the slack and clearance of thebrake-shoes, connections, and axle-boxes. In this movement the piston 51acts as a pump, unseating the check-valve 45 and drawing liquid from thereservoir 9 or directly from the suction-pipe 5, as the case may be.\Vhen the brakeshoes '7 come in contact with the wheels 2 and thepressure of the liquid on the outer side of the smaller piston 51 risessufficiently to overcome the pressure of the spring 1 1 on the piston43, said liquid-pressure, acting on the dilferential area of the piston13 above that of the connected valve 41, moves said piston to the right,thereby unseating the valve 41, and also closes communication with thereservoir 9 by seating the cheek-valve 4:5. The pressure from the branchpressure-pipe 5 is then exerted on the outer side of the piston 51. Thispiston being of materially larger diameter than the piston 51, asubstantial increase of pressure is exerted, by which increased pressurethe piston 51 is forced forward and applies the brakes with the maximumforce desired, the additional action of the piston 51 being analogous tothat which would be attained by an increase of leverage. lVhen the shoesare so worn that the piston 51 strikes the shoulder 53 before fullapplication of the brakes, the liquid-pressure transmitted to the piston56 through the passage 64t on the unseating of the valve 65 completesthe application. In order to release the brakes, pressure is released inthe pressure-pipe 5", and the spring 22 forces back the pistons 56 5151. The liquid between the pistons 51 and 51 unseats the check-valve 42and passes back to the pipes 5 and 5 As the pressure is released in thepipe 5 the spring 43 seats the valve 41. Liquid from the outer side ofthe piston 51 passes to the pipes 5 and 5 The modification illustratedin Figs. 3 and 4 difiers from that above described in the particularthat the cylinder 6 is provided with a piston 51 which moves in oppositedirection to the pistons 51 and 56, its relations to said pistons beingsimilar to that of the piston 13 to the piston 15 in Patent No. 574,665.It also differs as to its controlling-valve mechanism, which is amodified and simplified form of that of said Patent No. 574,665. Thebrakecylinder 6, pistons 51 and 56, passage 64, and check-valve aresimilar in all essential particulars to the correspondingly-numberedmembers in the construction first described; but the smallerbrake-cylinder 6 does not, as in the former instance, communicate withthe larger brake-cylinder, but is separated therefrom by an interposedhead 6", and the piston 51 of the smaller cylinder moves in 0ppositedirection to the pistons 51 and 56 of the larger cylinder. A rod 14,which abuts against the piston 51, is coupled by a pin 14" to one end ofa brake-lever 17, the opposite end of which is connected by a brake-rod25 to the brake-beam (not shown) of one pair of wheels of the car. A rod16, which abuts against the piston 56 of the larger cylinder, is coupledby a pin 16 to one end of a brakelever 17 the opposite end of which isconnected by a brake-rod 25 to the brake-beam 26 of another pair ofwheels of the car. The brake-levers 17 17 a are intermediately connectedby a brake-rod 18. The supply and discharge of liquid to and from thebrakecylinders 6 6 in the application and release, respectively, of thebrakes are effected by a valvular mechanism inclosed in a casing 40,which communicates by a branch pipe 5, leading to a port in a valve-facein the casing, with a delivery or pressure pipe 5 which extends to apump or other source of pressure and which may serve also for therelease of pressure on the cessation of operation of the pump or therelease of the pressure within it. A pipe 5 connects another port in thevalveface of the casing with the larger brake-cylinder 6 between thehead 6 thereof and the piston 51, and the pipe 5 is connected by arelease-pipe 5, controlled by a release checkvalve 52, with thepressure-pipe 5". A pipe 5 leads from one end of the casing 40 to thesmaller brake-cylinder 6 The valve-face ports of the pipes 5 and 5 arecontrolled by a slide-valve 47 ,which is provided with a port 47 and isconnected to a stem 48, upon which is fixed a piston 50, which closesthe end of the casing 40 opposite that to which the pipe 5 is connected,said piston abutting against a spring 51, contained in an extension 40of the casing, the tension of which spring is adjustable by a set-screw51 in the ordinary manner.

In the construction shown in Fig. 3 the ap paratus is assumed to belocated on a trailercar, in which case only the pipe 5", connected withthe pump, would be required. When used on a motor-car, the pipe 5 (shownin dotted lines) would be required to connect the pump to the reservoircontaining the liquid. As in the instance first described, thebrakecylinder spaces behind the pistons are supposed to be full ofliquid and excess slack has been taken up, forcing the pistons 51 and 56apart and interposing liquid between the pistons, which liquid is at alltimes subject to the pressure exerted by the spring 22. In effecting anapplication of the brakes liquid under pressure enters the valvecasing40 from the pressure-pipe 5 through the port communicating with thebranch pipe 5 and the port 47 of the slide-valve 47 (see Figs. 3 and 5)and passes from the casing through the pipe 5 to the smallerbrake-cylinder 6, forcing out the piston 51 thereof, and thereby takingup the slack of the connections and bringing the brake-shoes against thewheels, as Well as moving the axle-boxes up to their bearings in thepedestals. The pressure exerted by the liquid on the piston 51 istransferred through the levers and connecting-rods to the brake-beams,and as the piston 56 and its push-rod l6 constitute the fulcrum orabutment at which the series of levers ends a force equal to thatexerted by the liquid on the piston 51 will be transferred to the piston56 and by it through the interposed liquid to the piston 51 and to theliquid on the left side thereof. This pressure per square inch will beas the relative areas of the two pistons. When the pressure in thevalve-casing 40 exceeds the pressure of the spring 51 on thecontrolling-valve piston 50, the controllingvalve 47 is moved by saidpiston to the right until the ports are line and line, (see Fig. 6,)cutting off communication with the pressurepipe 5 and locking the liquidin the cylinder 6 and opening slightly the port to the cavity of theslide-valve 47 and from said cavity to the pipe 5 At this time thepressure from the pump in the pipe 5 holds the check-valve 52 closedagainst the pressure on the inner side of the piston 51 of the largercylinder 6, said piston having been theretofore subjected to suchpressure from the piston of the smaller cylinder through thelever-and-link connections between them. Liquid then passes from thepipe 5 through the recess or cavity of the valve 47 and the pipe 5 intothe cylinder 6, moving the piston 51 thereof to the right, said piston,through the liquid interposed between it and the piston 56, also movingthe piston 56 in the same direction. As soon as the pressure passes intothe larger cylinder the direction of pressure is reversed and the pistonof the smaller cylinder becomes the fulcrum, the pressure per squareinch in the smaller cylinder rising in proportion to the relativetransverse areas of the cylinders. This rise in pressure furthercompresses the spring 51 and forces the piston 50 of thecontrolling-valve to the end of its stroke to the right, fully openingthe ports between the pipes 5 and 5, as shown in Fig. 7. The piston 56moves faster than the piston 51 by reason of being of smaller diameter,and the traverse of the piston 51 is very short. If by reason of wearthe piston 51 strikes the shoulder 53, liquid passes into the spacebetween it and the piston 56 by unseating the check-valve 65. Thismovement of the pistons 51 and 56 applies the brakes with the desireddegree of force, and the pressure reacts through the brake-levers andconnections, the pin 11 acting as a fulcrum, and proportionately raisesthe pressure in the smaller cylinder 6. Upon the release of pressure inthe pipe 5, which is effected only to such degree as not to dischargesufficient liquid from the cylinder 6 to permit the piston 51 to come toa bearing against the head 6, liquid passes from the cylinder 6 on theleft side of the piston 51, unseating the checkvalve 52, and therebyreleasing pressure from the inner side of the piston 51, and passes backthrough the release-pipe 5 to the pipe 5 the check-valve permitting itspassage independently of the controlling-valve 47, the movement of whichin regular sequence is not for this purpose essential. The instant thatthe pressure on the inner side of the piston 51 of the larger cylinderfalls below that at which the controlling-valve was held in the positionshown in Fig. 6 the piston 51 of the larger cylinder again becomes thefulcrum or abutment for that of the smaller cylinder, thereby slightlyrelieving the pressure in the smaller cylinder and valve-casing 40. Thepistons 51 and 56 are moved inward by the spring 22, and the pressure onthe piston 51 of the smaller cylinder is reduced to a point below thetension of the controllingvalve spring 51, which thereupon brings thecontrolling-valve 47 to the position shown in Fig. 8, slightly openingthe port to the pipe 5 allowing a portion of the liquid to escape fromthe smaller cylinder 0 and relieving the pressure in said cylinder andin the valvecasing 40, when the spring forces the valve to the positionshown in Figs. 3 and 5 and allows the liquid-pressure acting on thepiston 51" to be released through the pipe 5 and the port 47 of thecontrolling-valve.

Instead of employing a connection between the stem of the valve 05 andthe cap 08 of its casing as a means for manually unseating said valve bymovement of the cap, as hereinbefore described, the same function may beperformed by providing the cap 68 with an ordinary stnfling-box 70 andextending the valve-stem through the stuffing-box so as to be accessibleto the direct application of the hand of the operator, as shown in Fig.9.

Such construction I therefore specify as a substitute for that beforedescribed and for the purposes of my invention deem it a mechanicalequivalent therefor.

I claim as my invention and desire to secure by Letters Patent- 1. In abrake apparatus, the combination, substantially as set forth, of abrake-cylinder, a fluid-supply pipe leading thereinto, a piston fittedon a counterbore at the supply end of said cylinder, a piston fitted totraverse in a smaller bore extending from the counterbore toward theopposite end of the cylinder, apiston-rod adapted to receive pressurefrom the smaller piston, a retract-ingspring bearing on said smallerpiston, a passage leading from the supply-pipe to the space between thepistons, and a spring-seated valve seated in an external casing andcontrolling said passage, said valve operating automatically foradmission and being adapted for manual operation for release.

2. In a brake apparatus, the combination, substantially as set forth, ofa brake-cylinder, a fluid-supply pipe leading thereinto, a piston fittedin a counterbore at the supply end of said cylinder, a piston fitted totraverse in a smaller bore extending from the counterbore toward theopposite end of the cylinder, a piston-rod adapted to receive pressurefrom the smaller piston, a retractingspring bearing on said smallerpiston, a passage leading from the supply-pipe to the space between thepistons, a spring-seated valve fitted in an external casing andcontrolling said passage, and a removable cap connected to said casingfor manually unseating said valve.

3. In a brake apparatus, the combination,

piston, the supplemental piston being adapted to be moved by pressureimparted by the main piston through an interposed volume of liquid, asmaller brake-cylinder, a piston fitted therein, a brake-shoe,connections through which pressure on the pistons is imparted to thebrake-shoe, a passage from a source of fluid-pressure supply to thesmaller cylinder, a valvular mechanism, actuated by oppositely-exertedfluid and spring pressures, through which valvular mechanism andpassages controlled thereby, fluid under pressure is delivered from asupply and release pipe to the main piston of the larger cylinder and tothe space between the main and supplemental pistons of the largercylinder, and a release check-valve controlling communication betweenthe fluid supply and release pipe and the larger cylinder.

4. In a brake apparatus, the combination, substantially as set forth, oftwo brake-cylinders of different diameters, a main piston fitted in acounterbore at the supply end of the larger cylinder, a supplementalpiston fitted to traverse in a smaller bore extending from thecounterbore toward the opposite IIO IIS

end of the larger cylinder, a passage leading from the supply end of thelarger cylinder to the space between the pistons thereof, aspring-seated valve controlling said passage, a piston fitted totraverse in the smaller cylinder, a brake-shoe, connections throughwhich fluid-pressure on the pistons is imparted to the brake-shoe, apassage from a source of fluid-pressure supply to the smaller cylinder,through which fluid is primarily supplied to the piston of the smallercylinder, to take up the clearance and slack of the brake connectionsand impart initial pressure of the brake-shoe to a wheel, a valvularmechanism actuated by oppositely-exerted fluid and spring pressures,through which valvular mechanism and passages controlled thereby fluidis supplied to the larger cylinder to effeet the application of thebrake-shoe with determined greater final force by a comparatively shorttraverse of the pistons of the larger cylinder, and a releasecheck-valve controlling communication between a fluid supply and releasepipe and the larger cylinder.

5. In a brake apparatus, the combination, substantially as set forth, ofa larger brakecylinder, having a main and a supplemental piston,thesupplemental piston being adapted to be moved by pressure imparted bythe main piston through an interposed volume of liquid, a smallerbrake-cylinder communicating with the larger cylinder, a piston fittingsaid smaller cylinder and fixed to the main piston of the largercylinder, a brake-shoe, connections through which pressure on thepistons is imparted to the brake-shoe, a passage from a source offluid-supply to the smaller cylinder, a Valvular mechanism, actuated byoppositely-exerted fluid and spring pressures,

through which valvular mechanism and passages controlled thereby, fluidis supplied to the main piston of the larger cylinder, and a releasecheck-valve controlling communication between a fluid supply and releasepipe and the larger cylinder.

6. In a brake apparatus, the combination, substantially as set forth, ofa larger and a smaller brake-cylinder, pistons fitting said cylinders, abrake-shoe, connections through which pressure on the pistons isimparted to the brake-shoe, a pipe for the supply and release of fluidunder pressure, a valve controlling communication between said pipe andthe larger cylinder, a piston connected to said valve, and subject tothe pressure in the fluid supply and release pipe, a spring acting onsaid piston in direction opposite to that of the action of pressurethereon, and a release check-valve controlling a communication betweenthe larger cylinder and the fluid supply and release pipe.

7. In a brake apparatus, the combination,

substantially as set forth, of a larger and a smaller brake-cylinder,pistons fitting said cylinders, a brake-shoe, connections through whichpressure on the pistons is imparted to the brake-shoe, a valve-casinghaving connections to a pipe for the supply and release of fluid underpressure, and to the larger brake-cylinder,a controlling-valvetraversing in said casing and adapted to establish comcontrolling acommunication between the larger cylinder and the fluid supply and re=-lease pipe.

FRANCIS L. CLARK.

Witnesses:

J. SNOWDEN BELL, WALTER L. MERWnv,

' munication between the larger cylinder and

